1. Introduction to nanocellulose

Nanocellulose is a nanoscale material derived from natural cellulose and prepared by mechanical, chemical or enzymatic methods Its diameter is between . 5–100 nm , which is much smaller than the wavelength of visible light, making it outstanding in terms of optical performance. As a new green, renewable, and degradable functional material, nanocellulose has attracted great attention in fields such as transparent films, flexible displays, and optical devices due to its high transparency and optical stability.

2. Why does nanocellulose have high light transmittance?

The reason why nanocellulose can achieve a high light transmittance of 85–95% is essentially due to the following three reasons:

1. The diameter of the fibril is much smaller than the wavelength of visible light

The wavelength of visible light is 400–700 nm , while the diameter of nanocellulose is only a few nanometers to tens of nanometers, which is much lower than the wavelength of light, so that light is almost not scattered in the material, and the transparency is naturally higher.

2. Highly uniform three-dimensional network structure

The nanocellulose film forms a highly ordered hydrogen bond network during the film formation process. The structure is uniform and transparent, and does not cause light scattering and haze increase like traditional pulp fibers.

3. Optical stability brought by high crystallinity

Cellulose nanocrystals ( CNC ) have high crystallinity, up to 60-90% , which can improve optical uniformity and enable the transparent film to maintain stable light transmission performance under different temperatures and humidity.

These unique properties make nanocellulose a new optical substrate that outperforms many traditional transparent materials.

3. The core value brought by the high transmittance of nanocellulose

1. Transparent film material that can replace PET and glass

Nanocellulose transparent film not only has high light transmittance, but also has:

higher mechanical strength

Better heat resistance (can withstand more than 200°C )

Completely degradable, environmentally friendly and harmless

This makes it an important upgrade direction for transparent packaging materials and optical films.

2. Ideal transparent base material for flexible displays

Flexible display devices require materials that are transparent, fold-resistant, and tough at the same time.
Nanocellulose transparent film has:

Thin and bendable

High light transmittance keeps the picture clear

Good compatibility with coating materials

It has been used to research new displays such as OLED substrates, touch screen coatings, and foldable electronic paper .

3. Transparent substrate and functional layer of solar cells

For new energy devices such as organic photovoltaic cells ( OPV ) and quantum dot solar cells, transparent and sustainable base materials are crucial.
Nanocellulose transparent film can be used as:

Transparent conductive layer matrix

Solar cell packaging film

Support layer for flexible solar modules

It not only improves the light transmission efficiency, but also meets the industrial needs of lightweight and degradable.

4. Optical devices and lens materials

With low haze and high refractive index uniformity, nanocellulose can be used to manufacture:

light diffusion film

clear lenses

filter film

Highly transparent coating

Suitable for precision optical equipment and smart wearable hardware.

4. Comparison with traditional transparent materials (more intuitive)

Material Type	Light transmittance	Flexibility	Environmental protection	heat resistance	Comprehensive advantages
Glass	高	差	Non-degradable	高	Traditional transparent materials
PET film	高	medium	Difficult to degrade	medium	Commonly used transparent films
ITO glass substrate	高	差	Non-degradable	高	Shows useful but brittle
Nanocellulose transparent film	85–95% (very high)	Excellent, foldable	Completely degradable	High temperature resistance	The most promising new generation of transparent materials

Nanocellulose transparent films have significant advantages in lightweight, environmental protection, and film-forming performance, and are an important direction for future transparent functional materials.

V. Conclusion

Nanocellulose not only has high mechanical strength, biodegradability and other properties, but its high light transmittance makes it a star material in the fields of flexible displays, transparent films and optical devices. With further optimization of the preparation process and lower costs, nanocellulose transparent films will usher in wider industrial applications in industries such as electronic information, food packaging, sustainable energy, and optical technology .